Systems for sensing tire conditions and displaying sensed tire condition information to a vehicle occupant are known. Often, such systems are known as tire pressure monitoring (“TPM”) systems even though the system may sense tire conditions in addition to pressure, such as tire temperature. Such TPM systems may include a tire-based sensor assembly that senses, for example, the air pressure and temperature inside its associated tire and transmits the sensed tire condition information to a vehicle-based receiver, i.e., a receiver mounted in the vehicle. The transmitted sensed tire condition signal may be a coded radio frequency (“RF”) signal. The vehicle-based receiver is connected to a display located in the vehicle cabin that can display, for example, a warning signal to the vehicle operator when an under-inflated tire pressure condition exists or an over-heated tire condition occurs.
Each tire-based sensor assembly may have a unique identification (“ID”) code associate therewith. The tire-based sensor assembly may transmit a signal that includes its associated unique ID code along with the sensed tire condition. The vehicle-based receiver can associate the received tire signal and unique ID with a particular tire location on the vehicle such as front right (“FR”), front left (“FL”), rear right (“RR”), or rear left (“RL”). By associating the tire ID with the tire location on the vehicle, the vehicle-based receiver is able to display the sensed tire condition information at each particular tire location so the vehicle operator can identify which tire (i.e., tire location) has a sensed, improper condition.
Associating a tire location with a tire-based transmitted ID code for each of the tire locations may require a “learning” process by the vehicle-based receiver. Methods have been proposed to accomplish this learning function including using signal interrogation in which each tire-based sensor assembly includes a receiver that is separately interrogated from a transmitter located outside of the tire using, for example, a low frequency (“LF”) interrogation signal. In response to receiving an interrogation signal, the tire-based sensor assembly transmits a response signal having its associated unique ID. Upon receipt of the response signal from the tire-based unit, the vehicle-based receiver associates that unique tire ID with that tire location since the system “knows” which tire location was just interrogated. The vehicle-based system stores tire-based sensor IDs and tire location associations in memory for later use in its display operation.
Certain vehicles have multiple tires per side per axle. One such vehicle is a pickup truck referred to as a “dually.” A dually pickup truck has four wheels/tires on the rear axle with two tires on each side, i.e., multiple tires per axle per side. Other vehicles, such as semi-trailers, may also have two tires per side on certain axles. Two tires on one side of a vehicle on the same axle are referred to herein as a tire pair.